Francis Charles Seymour Conway (1777-1842), 3rd Marquess of Hertford, was the son of the 2nd Marquess.

He was Vice-Chamberlain in the Royal Household 1812-21. In 1798 he married, much against his parents’ wishes, Maria Fagnani, the illegitimate daughter of the Marchesa Fagnani, a former dancer.

She greatly increased the family’s wealth through substantial bequests from the 4th Duke of Queensberry (‘Old Q’) and his associate George Selwyn. The future 4th Marquess was born of this marriage in 1800, but soon after the 3rd Marquess and Maria visited Paris in 1802 they became estranged and from that time led separate lives. She remained in Paris, while the 3rd Marquess established splendid residences in London at Dorchester House (on the site of the present Dorchester Hotel) and at St Dunstan’s Villa in Regent’s Park (demolished in 1937).

His later life was devoted largely to dissipation and foreign travel to the extent that he was the model for the sinister figure of Lord Steyne in Thackeray’s Vanity Fair. He also appears as Lord Monmouth in Disraeli’s Coningsby. The 3rd Marques was a considerable connoisseur. He bought Titian’s Perseus and Andromeda and seventeenth-century Dutch paintings such as Netscher’s The Lace Maker and Rembrandt’s Good Samaritan as well as French furniture, gilt bronzes and Sèvres porcelain.

He also acted as a saleroom agent for the Prince of Wales, for whom he bought forty outstanding Dutch and Flemish pictures which remain in the Royal Collection. Both men were attracted by the luxury and refinement of eighteenth-century French art and, like many other English collectors, profited from the break-up of many Continental collections during the French Revolution and the Napoleonic wars.